Pub Date : 2023-10-18DOI: 10.1088/1674-4527/ad0497
Hui-Ying Deng, Zhaoyang Peng, Jia-Ming Chen, Dan Zhu
Abstract In gamma-ray burst (GRB) prompt emission, there is still no consistent conclusion if the precursor and the main burst share the same origin. In this paper, we try to study the issue based on the relationship between pulse width and energy of the precursor and main burst. We systematically search the light curve data observed by Swift/BAT and Fermi/GBM, and find 13 long bursts with well-structured precursors and main bursts. After fitting the precursor light curve of each different energy channel with the Norris function, we find that there is not only a power-law relationship between precursor width and energy, but also a power-law relationship between the ratio of the rising width to the decaying width and energy. By comparing the relationship between the precursors and the main burst pulses, we find that the distribution of the precursors and the relationship between the power law indices are roughly the same as those of the main burst. In addition, it is found that the precursor width distribution as well as the upper limit of the pulse width ratio do not exceed 1 and are asymmetric, which is also consistent with the main burst. These indicate that the precursor and the main burst are indistinguishable, and the precursor and the main burst may have the same physical origin.
{"title":"A comparative study of the power-law relationship between the pulse width and energy of precursor and main burst","authors":"Hui-Ying Deng, Zhaoyang Peng, Jia-Ming Chen, Dan Zhu","doi":"10.1088/1674-4527/ad0497","DOIUrl":"https://doi.org/10.1088/1674-4527/ad0497","url":null,"abstract":"Abstract In gamma-ray burst (GRB) prompt emission, there is still no consistent conclusion if the precursor and the main burst share the same origin. In this paper, we try to study the issue based on the relationship between pulse width and energy of the precursor and main burst. We systematically search the light curve data observed by Swift/BAT and Fermi/GBM, and find 13 long bursts with well-structured precursors and main bursts. After fitting the precursor light curve of each different energy channel with the Norris function, we find that there is not only a power-law relationship between precursor width and energy, but also a power-law relationship between the ratio of the rising width to the decaying width and energy. By comparing the relationship between the precursors and the main burst pulses, we find that the distribution of the precursors and the relationship between the power law indices are roughly the same as those of the main burst. In addition, it is found that the precursor width distribution as well as the upper limit of the pulse width ratio do not exceed 1 and are asymmetric, which is also consistent with the main burst. These indicate that the precursor and the main burst are indistinguishable, and the precursor and the main burst may have the same physical origin.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135824750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-18DOI: 10.1088/1674-4527/ad0498
Xi-Long Fan, Peizheng Wang, Jin Li, Nan Yang
Abstract The error propagation among estimated parameters reflects the correlation among the parameters. We study the capability of machine learning of ``learning" the correlation of estimated parameters. We show that machine learning can recover the relation between the uncertainties of different parameters, especially, as predicted by the error propagation formula. As a proof-of-principle test, a toy model of linear relation with Gaussian noise is presented. We found that the predictions obtained by machine learning indeed indicate the information about the law of error propagation and the distribution of noise. Gravitational lensing can be used to probe both astrophysics and cosmology. As a practical application, we show that the machine learning is able to intelligently find the error propagation among the gravitational lens parameters (effective lens mass $M_{L}$ and Einstein radius $theta_{E}$) in accordance with the theoretical formula for the singular isothermal ellipse (SIE) lens model. The relation of errors of lens mass and Einstein radius, (e.g. the ratio of standard deviations $mathcal{F}=sigma_{hat{ M_{L}}}/ sigma_{hat{theta_{E}}}$) predicted by the deep convolution neural network are consistent with the error propagation formula of SIE lens model. Error propagation plays a crucial role in identifying the physical relation among parameters, rather than a coincidence relation, therefore we anticipate our case study on the error propagation of machine learning predictions could extend to other physical systems on searching the correlation among parameters.
{"title":"Understanding the predication mechanism of deep learning through error propagation among parameters in strong lensing case","authors":"Xi-Long Fan, Peizheng Wang, Jin Li, Nan Yang","doi":"10.1088/1674-4527/ad0498","DOIUrl":"https://doi.org/10.1088/1674-4527/ad0498","url":null,"abstract":"Abstract The error propagation among estimated parameters reflects the correlation among the parameters. We study the capability of machine learning of ``learning\" the correlation of estimated parameters. We show that machine learning can recover the relation between the uncertainties of different parameters, especially, as predicted by the error propagation formula. As a proof-of-principle test, a toy model of linear relation with Gaussian noise is presented. We found that the predictions obtained by machine learning indeed indicate the information about the law of error propagation and the distribution of noise. Gravitational lensing can be used to probe both astrophysics and cosmology. As a practical application, we show that the machine learning is able to intelligently find the error propagation among the gravitational lens parameters (effective lens mass $M_{L}$ and Einstein radius $theta_{E}$) in accordance with the theoretical formula for the singular isothermal ellipse (SIE) lens model. The relation of errors of lens mass and Einstein radius, (e.g. the ratio of standard deviations $mathcal{F}=sigma_{hat{ M_{L}}}/ sigma_{hat{theta_{E}}}$) predicted by the deep convolution neural network are consistent with the error propagation formula of SIE lens model. Error propagation plays a crucial role in identifying the physical relation among parameters, rather than a coincidence relation, therefore we anticipate our case study on the error propagation of machine learning predictions could extend to other physical systems on searching the correlation among parameters.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135825499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-18DOI: 10.1088/1674-4527/ad0499
Jianghui Ji, Dongjie Tan, Chunhui Bao, Xiumin Huang, Shoucun HU, Yao Dong, Su Wang
Abstract The Standards of Fundamental Astronomy (SOFA) is a service provided by the International Astronomical Union (IAU) that offers algorithms and software for astronomical calculations, which was released in two versions by FORTRAN 77 and ANSI C, respectively. textbf{In this work, we implement the python package PyMsOfa for SOFA service by three ways: (1) a python wrapper package based on a foreign function library for Python (ctypes), (2) a python wrapper package with the foreign function interface for Python calling C code (cffi), and (3) a python package directly written in pure python codes from SOFA subroutines.} The package PyMsOfa has fully implemented 247 functions of the original SOFA routines. In addition, PyMsOfa is also extensively examined, which is exactly consistent with those test examples given by the original SOFA. This python package can be suitable to not only the astrometric detection of habitable planets of the Closeby Habitable Exoplanet Survey (CHES) mission citep{ji2022ches}, but also for the frontiers themes of black holes and dark matter related to astrometric calculations and other fields. The source codes are available via https://github.com/CHES2023/PyMsOfa.
{"title":"PyMsOfa: A Python Package for the Standards of Fundamental Astronomy (SOFA) Service","authors":"Jianghui Ji, Dongjie Tan, Chunhui Bao, Xiumin Huang, Shoucun HU, Yao Dong, Su Wang","doi":"10.1088/1674-4527/ad0499","DOIUrl":"https://doi.org/10.1088/1674-4527/ad0499","url":null,"abstract":"Abstract The Standards of Fundamental Astronomy (SOFA) is a service provided by the International Astronomical Union (IAU) that offers algorithms and software for astronomical calculations, which was released in two versions by FORTRAN 77 and ANSI C, respectively. textbf{In this work, we implement the python package PyMsOfa for SOFA service by three ways: (1) a python wrapper package based on a foreign function library for Python (ctypes), (2) a python wrapper package with the foreign function interface for Python calling C code (cffi), and (3) a python package directly written in pure python codes from SOFA subroutines.} The package PyMsOfa has fully implemented 247 functions of the original SOFA routines. In addition, PyMsOfa is also extensively examined, which is exactly consistent with those test examples given by the original SOFA. This python package can be suitable to not only the astrometric detection of habitable planets of the Closeby Habitable Exoplanet Survey (CHES) mission citep{ji2022ches}, but also for the frontiers themes of black holes and dark matter related to astrometric calculations and other fields. The source codes are available via https://github.com/CHES2023/PyMsOfa.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135824930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-17DOI: 10.1088/1674-4527/acfae1
wenjun Zhang, Xiaohui Sun, Jie Wang
Abstract We present a new total intensity image of M31 at 1.248 GHz, observed with the Five-hundred-meter Aperture Spherical radio telescope (FAST) with an angular resolution of 4′ and a sensitivity of about 16 mK. The new FAST image clearly reveals weak emission outside the ring due to its high sensitivity on large-scale structures. We derive a scale length of 2.7 kpc for the cosmic ray electrons and find that the cosmic ray electrons propagate mainly through diffusion by comparing the scale length at 4.8 GHz. The spectral index of the total intensity varies along the ring, which can be attributed to the variation of the spectra of synchrotron emission. This variation is likely caused by the change of star formation rates along the ring. We find that the azimuthal profile of the non-thermal emission can be interpreted by an axisymmetric large-scale magnetic field with varying pitch angle along the ring, indicating a complicated magnetic field configuration in M31.
{"title":"New continuum observations of the Andromeda galaxy M 31 with FAST","authors":"wenjun Zhang, Xiaohui Sun, Jie Wang","doi":"10.1088/1674-4527/acfae1","DOIUrl":"https://doi.org/10.1088/1674-4527/acfae1","url":null,"abstract":"Abstract We present a new total intensity image of M31 at 1.248 GHz, observed with the Five-hundred-meter Aperture Spherical radio telescope (FAST) with an angular resolution of <?CDATA $4^{prime} $?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:mn>4</mml:mn> <mml:mo accent=\"false\">′</mml:mo> </mml:math> and a sensitivity of about 16 mK. The new FAST image clearly reveals weak emission outside the ring due to its high sensitivity on large-scale structures. We derive a scale length of 2.7 kpc for the cosmic ray electrons and find that the cosmic ray electrons propagate mainly through diffusion by comparing the scale length at 4.8 GHz. The spectral index of the total intensity varies along the ring, which can be attributed to the variation of the spectra of synchrotron emission. This variation is likely caused by the change of star formation rates along the ring. We find that the azimuthal profile of the non-thermal emission can be interpreted by an axisymmetric large-scale magnetic field with varying pitch angle along the ring, indicating a complicated magnetic field configuration in M31.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135944439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Jet precession has previously been proposed to explain the apparently repeating features in the light curves of a few gamma-ray bursts (GRBs). In this paper, we further apply the precession model to a bright GRB 220408B by examining both its temporal and spectral consistency with the predictions of the model. As one of the recently confirmed GRBs observed by our GRID CubeSat mission, GRB 220408B is noteworthy as it exhibits three apparently similar emission episodes. Furthermore, the similarities are reinforced by their strong temporal correlations and similar features in terms of spectral evolution and spectral lags. Our analysis demonstrates that these features can be well explained by the modulated emission of a Fast-Rise-Exponential-Decay (FRED) shape light curve intrinsically produced by a precessing jet with a precession period of 18.4−0.2+0.2 s, a nutation period of 11.1−0.2+0.2 s and viewed off-axis. This study provides a straightforward explanation for the complex yet similar multi-episode GRB light curves.
{"title":"GRB 220408B: A Three-Episode Burst from a Precessing Jet","authors":"Zijian Zhang, Yi-Han Iris Yin, Chenyu Wang, Xiangyu Ivy Wang, Jun Yang, Yan-Zhi Meng, Zi-Ke Liu, Guo-Yin Chen, Xiaoping Fu, Huaizhong Gao, Sihao Li, Yihui Liu, Xiangyun Long, Yong-Chang Ma, Xiaofan Pan, Yuanze Sun, Wei Wu, Zirui Yang, Zhizhen Ye, Xiaoyu Yu, Shuheng Zhao, Xutao Zheng, Tao Zhou, Qing-Wen Tang, Qiurong Qiu, Rong Zhou, Zhonghai Wang, Hua Feng, Ming Zeng, Binbin Zhang","doi":"10.1088/1674-4527/acfa59","DOIUrl":"https://doi.org/10.1088/1674-4527/acfa59","url":null,"abstract":"Abstract Jet precession has previously been proposed to explain the apparently repeating features in the light curves of a few gamma-ray bursts (GRBs). In this paper, we further apply the precession model to a bright GRB 220408B by examining both its temporal and spectral consistency with the predictions of the model. As one of the recently confirmed GRBs observed by our GRID CubeSat mission, GRB 220408B is noteworthy as it exhibits three apparently similar emission episodes. Furthermore, the similarities are reinforced by their strong temporal correlations and similar features in terms of spectral evolution and spectral lags. Our analysis demonstrates that these features can be well explained by the modulated emission of a Fast-Rise-Exponential-Decay (FRED) shape light curve intrinsically produced by a precessing jet with a precession period of <?CDATA ${18.4}_{-0.2}^{+0.2}$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:msubsup> <mml:mrow> <mml:mn>18.4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.2</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> s, a nutation period of <?CDATA ${11.1}_{-0.2}^{+0.2}$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:msubsup> <mml:mrow> <mml:mn>11.1</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.2</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> s and viewed off-axis. This study provides a straightforward explanation for the complex yet similar multi-episode GRB light curves.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135944430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-17DOI: 10.1088/1674-4527/acfc9b
Donghong Wu
Abstract Searching for exoplanets with different methods has always been the focus of astronomers over the past few years. Among multiple planet detection techniques, astrometry stands out for its capability to accurately determine the orbital parameters of exoplanets. In this study, we examine the likelihood of extraterrestrial intelligent civilizations detecting planets in our solar system using the astrometry method. By conducting injection-recovery simulations, we investigate the detectability of the four giant planets in our solar system under different observing baselines and observational errors. Our findings indicate that extraterrestrial intelligence could detect and characterize all four giant planets, provided they are observed for a minimum of 90 yr with signal-noise ratios exceeding 1. For individual planets such as Jupiter, Saturn, and Neptune, a baseline that surpasses half of their orbital periods is necessary for detection. However, Uranus requires longer observing baselines since its orbital period is roughly half of that of Neptune. If the astrometry precision is equal to or better than 10 μ as, all 8707 stars located within 30 pc of our solar system possess the potential to detect the four giant planets within 100 yr. Additionally, our prediction suggests that over 300 stars positioned within 10 pc from our solar system could detect our Earth if they achieve an astrometry precision of 0.3 μ as.
{"title":"The possibility of detecting our solar system through astrometry","authors":"Donghong Wu","doi":"10.1088/1674-4527/acfc9b","DOIUrl":"https://doi.org/10.1088/1674-4527/acfc9b","url":null,"abstract":"Abstract Searching for exoplanets with different methods has always been the focus of astronomers over the past few years. Among multiple planet detection techniques, astrometry stands out for its capability to accurately determine the orbital parameters of exoplanets. In this study, we examine the likelihood of extraterrestrial intelligent civilizations detecting planets in our solar system using the astrometry method. By conducting injection-recovery simulations, we investigate the detectability of the four giant planets in our solar system under different observing baselines and observational errors. Our findings indicate that extraterrestrial intelligence could detect and characterize all four giant planets, provided they are observed for a minimum of 90 yr with signal-noise ratios exceeding 1. For individual planets such as Jupiter, Saturn, and Neptune, a baseline that surpasses half of their orbital periods is necessary for detection. However, Uranus requires longer observing baselines since its orbital period is roughly half of that of Neptune. If the astrometry precision is equal to or better than 10 μ as, all 8707 stars located within 30 pc of our solar system possess the potential to detect the four giant planets within 100 yr. Additionally, our prediction suggests that over 300 stars positioned within 10 pc from our solar system could detect our Earth if they achieve an astrometry precision of 0.3 μ as.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135944299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-17DOI: 10.1088/1674-4527/acfa58
dong Zhang, Rongbing Zhao, Zhen Yan, WeiHua ShangGuan, Qian Ye, Zhiqiang Shen, Qinghui Liu, jinqing Wang, Li Fu, Chu-Yuan Zhang, Dong-fang Song, Si-Yu Liu
Abstract The Tian-ma Radio Telescope (TMRT) applies an Active Surface System (ASFS), which corrects for large-scale deformations due to gravity and thermal on the primary reflector. The centralized and automated management of the ASFS using software has become a challenge, for which we have developed the TMRT Active Surface System Control Software (TASCS). This paper describes the design and implementation of TASCS for device control, status monitoring, human-computer interaction, and data management functionalities. TASCS adopts the open-source Tango Controls framework and distributes middleware technology to realize real-time automated adjustment of the primary reflector through remote centralized control of a large number of actuators. At present, it has been successfully deployed on the TMRT and has played an important role in Event Horizon Telescope observations.
{"title":"Distributed Control Software for the Active Surface System of Tian-ma Radio telescope","authors":"dong Zhang, Rongbing Zhao, Zhen Yan, WeiHua ShangGuan, Qian Ye, Zhiqiang Shen, Qinghui Liu, jinqing Wang, Li Fu, Chu-Yuan Zhang, Dong-fang Song, Si-Yu Liu","doi":"10.1088/1674-4527/acfa58","DOIUrl":"https://doi.org/10.1088/1674-4527/acfa58","url":null,"abstract":"Abstract The Tian-ma Radio Telescope (TMRT) applies an Active Surface System (ASFS), which corrects for large-scale deformations due to gravity and thermal on the primary reflector. The centralized and automated management of the ASFS using software has become a challenge, for which we have developed the TMRT Active Surface System Control Software (TASCS). This paper describes the design and implementation of TASCS for device control, status monitoring, human-computer interaction, and data management functionalities. TASCS adopts the open-source Tango Controls framework and distributes middleware technology to realize real-time automated adjustment of the primary reflector through remote centralized control of a large number of actuators. At present, it has been successfully deployed on the TMRT and has played an important role in Event Horizon Telescope observations.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135944429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-17DOI: 10.1088/1674-4527/ad0427
hailong zhang, Zhang Yazhou, Meng ZHANG, Jie WANG, Jian Li, Xinchen YE, Xin Pei
Abstract Aiming at the subband division of UWL (Ultra-Wide wideband Low-frequency) signal (frequency coverage range :704-4032 MHz) of Xinjiang 110 m radio telescope (QTT), a scheme of ultra-wide bandwidth signal is designed. Firstly, we analyze the effect of different window functions such as Hanning window, Hamming window and Kaiser window on the performance of FIR (Finite Impulse Response) digital filters, and implement a CS-PFB (Critical Sampling Polyphase Filter Bank) based on the Hamming window FIR digital filter. Secondly, we generate 3328 MHz simulation data of ultra-wideband pulsar baseband in the frequency range of 704-4032 MHz using the UBPB (Ultra-wide Bandwitdh Pulsar Baseband data generation) algorithm based on the 400 MHz bandwidth pulsar baseband data obtained from Parkes CASPSR observations. Thirdly, we obtain 26 subbands of 128 MHz based on CS-PFB and the simulation data, and the pulse profile of each subband by coherent dispersion, integration, and folding. Finally, the phase of each subband pulse profile is aligned by non-coherent dedispersion, and to generate a broadband pulse profile, which is basically the same as the pulse profile obtained from the original data using DSPSR. The experimental results show that the scheme of QTT UWL reception system is feasible, and the proposed channel algorithm in this paper is effective.
{"title":"Research on UWL signal channelization for Xinjiang 110 m radio telescope","authors":"hailong zhang, Zhang Yazhou, Meng ZHANG, Jie WANG, Jian Li, Xinchen YE, Xin Pei","doi":"10.1088/1674-4527/ad0427","DOIUrl":"https://doi.org/10.1088/1674-4527/ad0427","url":null,"abstract":"Abstract Aiming at the subband division of UWL (Ultra-Wide wideband Low-frequency) signal (frequency coverage range :704-4032 MHz) of Xinjiang 110 m radio telescope (QTT), a scheme of ultra-wide bandwidth signal is designed. Firstly, we analyze the effect of different window functions such as Hanning window, Hamming window and Kaiser window on the performance of FIR (Finite Impulse Response) digital filters, and implement a CS-PFB (Critical Sampling Polyphase Filter Bank) based on the Hamming window FIR digital filter. Secondly, we generate 3328 MHz simulation data of ultra-wideband pulsar baseband in the frequency range of 704-4032 MHz using the UBPB (Ultra-wide Bandwitdh Pulsar Baseband data generation) algorithm based on the 400 MHz bandwidth pulsar baseband data obtained from Parkes CASPSR observations. Thirdly, we obtain 26 subbands of 128 MHz based on CS-PFB and the simulation data, and the pulse profile of each subband by coherent dispersion, integration, and folding. Finally, the phase of each subband pulse profile is aligned by non-coherent dedispersion, and to generate a broadband pulse profile, which is basically the same as the pulse profile obtained from the original data using DSPSR. The experimental results show that the scheme of QTT UWL reception system is feasible, and the proposed channel algorithm in this paper is effective.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136034305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-17DOI: 10.1088/1674-4527/ad0429
Sergio Paron
Abstract The star forming processes strongly influence the ISM chemistry. 
Nowadays, there are available many high-quality databases at millimeter wavelengths. Using them, it is possible to carry out studies that review and deepen previous results. If these studies involve large samples of sources, it is preferred to use {bf direct} tools to study the molecular gas.
With the aim of testing these tools such as the use of the HCN/HNC ratio as a thermometer, and the use of H$^{13}$CO$^{+}$, HC$_{3}$N, N$_{2}$H$^{+}$, and C$_{2}$H as ``chemical clocks'', we present a molecular line study towards 55 sources representing {bf massive young stellar objects (MYSOs)} at different evolutive stages: infrared dark clouds (IRDCs), high-mass protostellar objects (HMPOs), hot molecular cores (HMCs) and {bf ultracompact hii~regions (UChii)}.
We found that the use of HCN/HNC ratio as an universal thermometer in the ISM should be taken with care because the HCN optical depth is a big issue that can affect the method. Hence, this tool should be used only after a careful analysis of the HCN spectrum, checking that no line, neither the main nor the hyperfine ones, present absorption features.
We point out that the analysis of the emission of H$^{13}$CO$^{+}$, HC$_{3}$N, N$_{2}$H$^{+}$, and C$_{2}$H could be useful to trace and distinguish regions among IRDCs, HMPOs and HMCs. 
The molecular line widths of these four species increase from the IRDC to the HMC stage, which can be a consequence of the gas dynamics related to the star-forming processes taking place in the molecular clumps. 
Our results do not only contribute with more statistics regarding to probe such chemical tools, useful to obtain information in large samples of sources, but also complement previous works through the analysis on other types of sources.
{"title":"Early phases of star formation: testing chemical tools","authors":"Sergio Paron","doi":"10.1088/1674-4527/ad0429","DOIUrl":"https://doi.org/10.1088/1674-4527/ad0429","url":null,"abstract":"Abstract The star forming processes strongly influence the ISM chemistry. &#xD;Nowadays, there are available many high-quality databases at millimeter wavelengths. Using them, it is possible to carry out studies that review and deepen previous results. If these studies involve large samples of sources, it is preferred to use {bf direct} tools to study the molecular gas.&#xD;With the aim of testing these tools such as the use of the HCN/HNC ratio as a thermometer, and the use of H$^{13}$CO$^{+}$, HC$_{3}$N, N$_{2}$H$^{+}$, and C$_{2}$H as ``chemical clocks'', we present a molecular line study towards 55 sources representing {bf massive young stellar objects (MYSOs)} at different evolutive stages: infrared dark clouds (IRDCs), high-mass protostellar objects (HMPOs), hot molecular cores (HMCs) and {bf ultracompact hii~regions (UChii)}.&#xD;We found that the use of HCN/HNC ratio as an universal thermometer in the ISM should be taken with care because the HCN optical depth is a big issue that can affect the method. Hence, this tool should be used only after a careful analysis of the HCN spectrum, checking that no line, neither the main nor the hyperfine ones, present absorption features.&#xD;We point out that the analysis of the emission of H$^{13}$CO$^{+}$, HC$_{3}$N, N$_{2}$H$^{+}$, and C$_{2}$H could be useful to trace and distinguish regions among IRDCs, HMPOs and HMCs. &#xD;The molecular line widths of these four species increase from the IRDC to the HMC stage, which can be a consequence of the gas dynamics related to the star-forming processes taking place in the molecular clumps. &#xD;Our results do not only contribute with more statistics regarding to probe such chemical tools, useful to obtain information in large samples of sources, but also complement previous works through the analysis on other types of sources.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135994318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We intend to study a modified version of the planar Circular Restricted Three-Body Problem (CRTBP) by incorporating several perturbing parameters. We consider the bigger primary as an oblate spheroid and emitting radiation while the small primary has an elongated body. We also consider the perturbation from a disk-like structure encompassing this three-body system. First, we develop a mathematical model of this modified CRTBP. We have found there exist five equilibrium points in this modified CRTBP model, where three of them are collinear and the other two are non-collinear. Second, we apply our modified CRTBP model to the Sun-Haumea system by considering several values of each perturbing parameter. Through our numerical investigation, we have discovered that the incorporation of perturbing parameters has resulted in a shift in the equilibrium point positions of the Sun-Haumea system compared to their positions in the classical CRTBP. The stability of equilibrium points is investigated. We have shown that the collinear equilibrium points are unstable and the stability of non-collinear equilibrium points depends on the mass parameter $mu$ of the system. Unlike the classical case, non-collinear equilibrium points have both a maximum and minimum limit of $mu$ for achieving stability. We remark that the stability range of $mu$ in non-collinear equilibrium points depends on the perturbing parameters. In context of the Sun-Haumea system, we have found that the non-collinear equilibrium points are stable.
{"title":"Studying the Equilibrium Points of the Modified Circular Restricted Three-Body Problem: the Case of Sun-Haumea System","authors":"Ibnu Nurul Huda, Budi Dermawan, Muhammad Bayu Saputra, Rifki Sadikin, Taufiq Hidayat","doi":"10.1088/1674-4527/acf978","DOIUrl":"https://doi.org/10.1088/1674-4527/acf978","url":null,"abstract":"We intend to study a modified version of the planar Circular Restricted Three-Body Problem (CRTBP) by incorporating several perturbing parameters. We consider the bigger primary as an oblate spheroid and emitting radiation while the small primary has an elongated body. We also consider the perturbation from a disk-like structure encompassing this three-body system. First, we develop a mathematical model of this modified CRTBP. We have found there exist five equilibrium points in this modified CRTBP model, where three of them are collinear and the other two are non-collinear. Second, we apply our modified CRTBP model to the Sun-Haumea system by considering several values of each perturbing parameter. Through our numerical investigation, we have discovered that the incorporation of perturbing parameters has resulted in a shift in the equilibrium point positions of the Sun-Haumea system compared to their positions in the classical CRTBP. The stability of equilibrium points is investigated. We have shown that the collinear equilibrium points are unstable and the stability of non-collinear equilibrium points depends on the mass parameter $mu$ of the system. Unlike the classical case, non-collinear equilibrium points have both a maximum and minimum limit of $mu$ for achieving stability. We remark that the stability range of $mu$ in non-collinear equilibrium points depends on the perturbing parameters. In context of the Sun-Haumea system, we have found that the non-collinear equilibrium points are stable.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135944593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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